Method for monitoring the road path of a truck and a floor conveyor

ABSTRACT

Method for monitoring the travel path of an industrial truck, with the steps of: determination of a braking distance by a control device of the industrial truck on the basis of at least one operating parameter of the industrial truck, adjustment of a travel path area monitored by a monitoring device on the basis of the determined braking distance by adjusting the alignment of the monitoring device, deceleration of the industrial truck when an obstacle enters the travel path area monitored by the monitoring device.

The invention relates to a method for monitoring the travel path of an industrial truck, and to an industrial truck for carrying out said method.

Industrial trucks are known which have assistance systems for monitoring their surroundings. For example, monitoring devices can be provided which monitor the travel path of the industrial truck for obstacles in order to prevent a collision with persons or assets. For this purpose, sensors can be provided on the front side on a drive part of the industrial truck, or also on the rear side on a load part of the industrial truck. Such monitoring devices usually have a static detection area, thus monitor the travel path only at a fixed distance from the industrial truck. In this instance, however, the monitoring sensor system must be designed for the maximum braking distance of the industrial truck in order to always ensure timely stopping of the industrial truck. However, the braking distance of the industrial truck is not always the same, but rather is in particular dependent on the travel speed of the industrial truck and on the load weight carried by the industrial truck. Thus, especially at slow speeds or low load weight, an unnecessary or premature stopping of the industrial truck occurs. The operator thus loses time.

From EP 20 79 065 A2, an industrial truck is known with monitoring sensors for detecting obstacles, wherein the range of the sensors can be adapted on the software side depending on the speed of the industrial truck.

The invention is based on the object of providing a method for monitoring the travel path of an industrial truck, and an industrial truck for carrying out the method, which, given a simple implementation, always permit a braking of the industrial truck at the latest possible time.

The invention achieves the object via a method according to claim 1 and via an industrial truck according to claim 4. Preferred embodiments are part of the subclaims, the description, and Figures.

The method according to the invention for monitoring the travel path of an industrial truck includes the following steps:

-   -   determination of a braking distance by a control device of the         industrial truck on the basis of at least one operating         parameter of the industrial truck,     -   adjustment of a travel path area monitored by a monitoring         device on the basis of the determined braking distance by         adjusting the alignment of the monitoring device,     -   braking of the industrial truck when an obstacle enters the         travel path area monitored by the monitoring device.

The industrial truck according to the invention comprises at least one monitoring device for monitoring a travel path area for obstacles, a control unit, and at least one actuator acting on the monitoring device, the control unit being designed to determine a braking distance of the industrial truck on the basis of at least one operating parameter of the industrial truck, to control the at least one actuator for aligning the monitoring device, and to brake the industrial truck when an obstacle enters the monitored travel path area.

According to the invention, it is thus provided that a control device of the industrial truck evaluates one or more operating parameters of the industrial truck—continuously or at intervals—and determines a braking distance of the industrial truck on the basis of the operating parameters. In this instance, the control device determines in particular the minimum necessary braking distance, that is to say the distance that the industrial truck will at least require for stopping in the current operating situation. The braking distance is always selected such that a safe stopping of the industrial truck without contact with a possible obstacle is ensured.

The alignment of at least one monitoring device of the industrial truck is subsequently adjusted as a function of the determined braking distance, and a travel path area monitored by the monitoring device is thus adjusted. For this purpose, the industrial truck according to the invention has at least one actuator which acts on the at least one monitoring device. The at least one actuator is controlled by the control device and causes a mechanical adjustment of the alignment of the monitoring device. By aligning the monitoring device, the travel path area monitored by the monitoring device is shifted accordingly. For example, the at least one monitoring device may be tilted downward or upward or rotated to the sides, as will be explained later. When an obstacle, for example a person, enters the monitored travel path area of the monitoring devices, the industrial truck decelerates. In this instance, the presence of an obstacle within the monitored travel path area can be determined, for example, via the evaluation of signal propagation times, wherein signals emitted by the at least one monitoring device are reflected by the obstacle and subsequently captured again by the monitoring device.

The at least one monitoring device can be a laser scanner, for example.

According to the invention, a dynamic monitoring of the travel path for obstacles thus takes place. For example, the control unit can monitor the travel speed of the industrial truck as an operating parameter and, in the event of a high travel speed, shift the travel area monitored by the monitoring device further in front of the industrial truck than in the case of a low speed by aligning the monitoring device. In the event of a high speed, the industrial truck thus already detects obstacles entering the monitored travel path area at a greater distance from the industrial truck and enables a timely deceleration. At low travel speeds, the monitoring devices are in turn aligned in such a way that the monitored travel path area is located in the immediate vicinity of the industrial truck, and thus detection of obstacles also only takes place close to the industrial truck. Due to the low travel speed, safe stopping is nevertheless possible. Due to this dynamic travel path monitoring, the industrial truck is no longer stopped unnecessarily or too early, but rather ideally in the immediate vicinity of the obstacle. In this instance, the monitored travel path area is simply adjusted not on the software side but rather by a mechanical alignment of the monitoring device itself.

According to one embodiment of the invention, the at least one operating parameter is selected from the group of: a travel speed of the industrial truck, a steering angle of the industrial truck, a lifting height of a load part of the industrial truck, a load weight of a load transported by the industrial truck, a load center of gravity of a load transported by the industrial truck. One or more of the aforementioned can thus be used as operating parameters. For monitoring the said operating parameters, the industrial truck can have sensors which are respectively designated for this purpose and which are in contact with the control device. As a rule, the braking distance of the industrial truck increases, for example, at a high travel speed, given a large lifting height of the load part, or given a high load weight. In this event, the control device can align the monitoring device via the at least one actuator in such a way that the monitored travel path area is arranged at a correspondingly large distance from the industrial truck. In the event of a rather low travel speed, a low height of the load part, or a small load weight, the travel path area can again be located at a rather short distance from the industrial truck via corresponding alignment of the monitoring device. Depending on a steering angle of the industrial truck, the control device can, for example, align the at least one monitoring device in such a way that the monitored travel path area is adjusted to the left or right to the sides of the industrial truck. The monitored travel path area thus follows a steering movement. This is particularly expedient for cornering in warehouses.

According to one embodiment, the method includes the step of tilting the monitoring device about a horizontal axis for adjusting the monitored travel path area along a travel axis of the industrial truck, and/or swiveling the monitoring device about a vertical axis for adjusting the monitored travel path area to the sides of the industrial truck. The at least one actuator may also be designed to tilt the monitoring device about a horizontal axis in order to adjust the monitored travel path area along a travel axis of the industrial truck, and/or to swivel the monitoring device about a vertical axis in order to adjust the monitored travel path area to the sides of the industrial truck. In particular, at least two actuators may also be provided, wherein a first actuator is designed to tilt the monitoring device about a horizontal axis in order to adjust the monitored travel path area along a travel axis of the industrial truck, and a second actuator is designed to swivel the monitoring device about a vertical axis in order to adjust the monitored area to the sides. The at least one monitoring device can thus be aligned by tilting or swiveling the monitoring device. A tilting of the monitoring device about a horizontal axis denotes in this instance an alignment downward in the direction of the floor supporting the industrial truck, or upward in the opposite direction. The horizontal axis thus extends parallel to the floor, and in particular perpendicular to a direction of travel of the industrial truck. The swiveling of the at least one monitoring device denotes an alignment of the monitoring device to the left or right, that is to say to the sides of the industrial truck. The vertical axis is in this instance perpendicular to the floor, and in particular also perpendicular to the direction of travel. The tilting of the at least one monitoring device enables the monitored travel path area to be adjusted along the travel axis, and thus enables the monitored travel path area to be a different distance from the industrial truck. The swiveling of the monitoring devices allows the monitored travel path area to be adjusted to the right or left to the sides in deviation from the travel axis, which is particularly important in the case of cornering. The at least one monitoring device can in this instance in particular be swiveled to the sides as a function of the steering angle of the industrial truck, as already mentioned above. The at least one actuator of the industrial truck can be designed in such a way that it enables both the tilting and the swiveling of the monitoring devices. However, different actuators can also be provided for performing the aforementioned movements.

Hereinafter, the invention will be explained with reference to Figures. Shown are:

FIG. 1 shows an industrial truck according to the invention in a lateral view,

FIG. 2 shows the industrial truck from FIG. 1 in a plan view, and

FIG. 3 shows a control for adjusting the monitoring device(s).

FIGS. 1 and 2 show an industrial truck 10 with a load part 12 and a drive part 14. The load part 12 has two load forks 16 for receiving a load acting on the load forks 16 with a load weight L. The industrial truck 10 also has a driver's cab 18 for an operator, and an operating element 19 for the control device of the industrial truck. The reference symbol 20 schematically shows a control device of the industrial truck. On the front side of the industrial truck 10, a monitoring device 22 is arranged on the drive part 14, which monitoring device 22 can be aligned via an actuator 24. The monitoring device 22 generates an in particular cone-shaped detection area which allows the travel path area 40 of the travel path 30 to be monitored.

The control device 20 monitors one or more operating parameters of the industrial truck 10 by means of one or more sensors (not shown), and calculates a required braking distance of the industrial truck based thereon. Depending on the braking distance determined, the control device 20 controls the actuator 24, which in turn aligns the monitoring device 22. On the one hand, the actuator 24 can tilt the monitoring device 22 downward or upward about the horizontal axis H by changing a tilt angle α, and can swivel said monitoring device to the sides about the vertical axis V by varying a swivel angle β.

The monitored travel path area 40 shown in FIG. 1 is located quite close to the industrial truck 10. This setting is selected when the at least one operating parameter yields a rather short braking distance, for example on the basis of a low travel speed. This has the advantage that the industrial truck 10 does not decelerate too early due to the obstacle 32, and stops at a rather large distance therefrom. If the evaluation of the at least one operating parameter, for example the travel speed, results in a larger braking distance being necessary, the monitored travel path area 40 is adjusted further forward in the direction of travel along the travel axis F, starting from FIG. 1. In this instance, the tilt angle α is reduced and the obstacle 32 enters the monitored travel path area 40. The obstacle 32 is then detected by the monitoring device 22, and the industrial truck is decelerated. For decelerating, the control device 20 can, for example, control brakes (not shown) of the industrial truck 10. The industrial truck 10 can thus react to the obstacle 32 promptly even at an increased speed.

The monitoring device 22 can also be swiveled by the actuator 24 to the sides of the industrial truck 10 so that the angle β between a leg of the monitored travel path area 40 and the travel axis F is increased or decreased. The monitoring device 22 can be swiveled in particular as a function of a steering angle of the industrial truck 10. For example, if an operator located in the driver's cab 18 steers to the right via the operating element 19, the detection area and thus the monitored travel path area 40 can likewise move to the right (i.e., upward in FIG. 2). Obstacles entering the travel path can thus be detected early. When steering to the left, the monitored travel path area 40 can likewise be adjusted to the left (that is to say downward in FIG. 2). In this instance, the monitored travel path area 40 can be adjusted so far to the left by correspondingly strong swiveling of the monitoring device 22 that the obstacle 32 is no longer located within the monitored travel path area 40. In this instance, the obstacle 32 is not relevant to the industrial truck 10 since, due to the steering movement, the industrial truck 10 drives past the obstacle 32 along a left-hand curve. Thus, undesirable stopping of the industrial truck 10 due to the obstacle 32, from which no risk of collision arises in this instance, does not occur.

In principle, it can also be provided that two actuators are used for aligning the monitoring device 22. A first actuator may then be designed to tilt and a second actuator to swivel the monitoring device 22, as explained above.

FIG. 3 shows a control scheme with input and output values of the control device 20. As operating parameters, among other things a travel speed 102, a load 104, a load center of gravity 106, a lifting height 108 of the load part 12, and/or a steering angle 110 can, for example, be used in the control device 20. The control device 20 calculates, in particular in real time, a required braking distance of the industrial truck from the vehicle parameters 102-110. Depending on the calculated braking distance, the control device 20 outputs a target value α (reference symbol 112) for the tilt angle α to a first actuator 114, as well as a target value α (reference symbol 118) for the swivel angle β to the second actuator 120. The actuators 114, 120 then align the monitoring device 22 accordingly. The current angle setting of the first actuator 114 is monitored by a sensor and provided as actual value α (reference symbol 116) back to the control device 20. The current angle setting of the second actuator 120 is also monitored by means of a sensor, and the current actual value β of the swivel angle (reference symbol 122) is returned to the control device 20. By evaluating the actual values α, β, the current alignment of the monitoring device 22 is always known to the control device 20, such that an accurate adjustment of the alignment can take place.

In deviation from FIG. 3, however, it is also possible to provide only one actuator that can adjust both the tilt angle α and the swivel angle β. It can then be provided that both the target value α and the target value β are passed on by the control device 20 to this one actuator, and the actuator in turn aligns the monitoring device 22 and returns the respective actual values for α and β to the control device 20.

LIST OF REFERENCE SYMBOLS

-   10 Industrial truck -   12 Load part -   14 Drive part -   16 Load forks -   18 Driver's cab -   19 Operating element -   20 Control device -   22 Monitoring device -   24 Actuator -   30 Travel path -   32 Obstacle -   40 Monitored travel path area -   100 Control system -   102 Travel speed -   104 Load -   106 Load center of gravity -   108 Lifting height -   110 Steering angle -   112 Target value of the tilt angle -   114 First actuator -   116 Actual value of the tilt angle -   118 Target value of the swivel angle -   120 Second actuator -   122 Actual value of the swivel angle -   F Travel axis -   H Horizontal axis -   L Load weight -   V Vertical axis -   α Tilt angle -   β Swivel angle 

1-8. (canceled)
 9. A method for monitoring the travel path of an industrial truck, comprising the steps of: determining a braking distance of the industrial truck on the basis of at least one operating parameter of the industrial truck; adjusting a travel path area monitored by a monitoring device on the basis of the determined braking distance, by adjusting the alignment of the monitoring device; and, decelerating the industrial truck when an obstacle enters the travel path area monitored by the monitoring device.
 10. The method according to claim 9, wherein the step of adjusting a travel path area further comprises tilting the monitoring device about a horizontal axis for adjusting the monitored travel path area along a travel leg of the industrial truck.
 11. The method according to claim 9, wherein the step of adjusting a travel path area further comprises swiveling the monitoring device about a vertical axis for adjusting the monitored travel path area to either side of the industrial truck.
 12. The method according to claim 10, wherein the step of adjusting the travel path area further comprises tilting the monitoring device about a horizontal axis for adjusting the monitored travel path area along a travel leg of the industrial truck.
 13. The method according to claim 9, wherein the at least one operating parameter is selected from the group of: a travel speed of the industrial truck, a steering angle of the industrial truck, a lifting height of a load part of the industrial truck, a load weight of a load transported by the industrial truck, and a load center of gravity of a load transported by the industrial truck.
 14. An industrial truck, comprising: at least one monitoring device for monitoring a travel path area for the presence of obstacles therein, at least one actuator disposed in combination with the monitoring device, and a control unit configured to determine a braking distance of the industrial truck as a function of at least one operating parameter of the industrial truck, and controlling the at least one actuator to align the monitoring device such that the industrial truck decelerates when an obstacle enters the monitored travel path area.
 15. The industrial truck according to claim 14, wherein the at least one actuator is configured to tilt the monitoring device about a horizontal axis in order to adjust the monitored travel path area along a travel leg of the industrial truck.
 16. The industrial truck according to claim 14, wherein the at least one actuator is configured to swivel the monitoring device about a vertical axis to adjust the monitored travel path area to either side of the industrial truck.
 17. The industrial truck according to claim 14, further comprising first and second actuators, the first actuator configured to tilt the monitoring device about a horizontal axis in order to adjust the monitored travel path area along a travel leg of the industrial truck, and the second actuator configured to swivel the monitoring device about a vertical axis to adjust the monitored area to the either side of the industrial truck.
 18. The industrial truck according claims 14 wherein the at least one monitoring device includes a sensor for measuring an instantaneous tilt angle and wherein the control unit compares the instantaneous tilt angle to a calculated tilt angle for enhanced accuracy.
 19. The industrial truck according claims 14 wherein the at least one monitoring device includes a sensor for measuring an instantaneous swivel angle and wherein the control unit compares an instantaneous swivel angle to a target swivel angle for enhanced accuracy.
 20. The industrial truck according claims 14 wherein the at least one monitoring device includes sensors for measuring an instantaneous tilt and an instantaneous swivel angle and wherein the control unit evaluates the instantaneous tilt and swivel angles to a calculated tilt angle and a target swivel angle, respectively, for enhanced accuracy.
 21. The industrial truck according to claim 15 wherein the monitoring device is a laser scanner.
 22. The industrial truck according to claim 16 wherein the monitoring device is a laser scanner.
 23. The industrial truck according to claim 14, wherein the at least one operating parameter is selected from the group of: a travel speed of the industrial truck, a steering angle of the industrial truck, a lifting height of a load part of the industrial truck, a load weight of a load transported by the industrial truck, and a load center of gravity of a load transported by the industrial truck.
 24. The industrial truck according to claim 15, wherein the at least one operating parameter is selected from the group of: a travel speed of the industrial truck, a steering angle of the industrial truck, a lifting height of a load part of the industrial truck, a load weight of a load transported by the industrial truck, and a load center of gravity of a load transported by the industrial truck.
 25. The industrial truck according to claim 16, wherein the at least one operating parameter is selected from the group of: a travel speed of the industrial truck, a steering angle of the industrial truck, a lifting height of a load part of the industrial truck, a load weight of a load transported by the industrial truck, and a load center of gravity of a load transported by the industrial truck.
 26. The industrial truck according to claim 17, wherein the at least one operating parameter is selected from the group of: a travel speed of the industrial truck, a steering angle of the industrial truck, a lifting height of a load part of the industrial truck, a load weight of a load transported by the industrial truck, and a load center of gravity of a load transported by the industrial truck. 